Drivetrain is the group of components responsible for delivering engine power to the wheels. One of the components is of course the gearbox. Other components include a diferential, prop-shafts (in rear-wheel drive and 4-wheel drive vehicles), a transferbox (in 4 wheel drive vehicles), drive shafts and CV joints. In the case of front wheel drive cars the differential is incorporated to the gearbox and together they are called transaxles. We mentioned before possible faults that can occur to a gearbox. As with gearboxes, differentials and transferboxes can be subjects to internal damage and failure or oil leaks. Prop shafts have what is known as cross joints (or U-joints) which fail through time, CV joints can fail and of course their rubber CV boots are also subjects to wear.